Preprints
Filtering by Subject: Physical Sciences and Mathematics
The Influence of Dust Levels on Atmospheric Carbon Dioxide and Global Temperature
Published: 2020-11-13
Subjects: Physical Sciences and Mathematics
The purpose of this paper is to examine the causality between DUST, CO2 and temperature for the Vostok ice core data series [Vostok Data Series], dating from 420 000 years ago, and the EPICA C Dome data going back 800 000 years. In addition, the time-varying volatility and coefficient of variation in the CO2, dust and temperature is examined, as well as their dynamic correlations and [...]
Microseismicity appears to outline highly coupled regions on the Central Chile megathrust
Published: 2020-11-12
Subjects: Physical Sciences and Mathematics
We compiled a novel microseismicity catalog for the Central Chile megathrust (29-35◦S), comprising 8750 earthquakes between 04/2014 and 12/2018. These events describe a pattern of three trenchward open half-ellipses, consisting of a continuous, coast-parallel seismicity band at 30-45 km depth, and narrow elongated seismicity clusters that protrude to the shallow megathrust and separate largely [...]
On the use of rock physics models for studying the critical zone
Published: 2020-11-12
Subjects: Geophysics and Seismology, Physical Sciences and Mathematics, Sedimentology
How effective are rock physics models for relating seismic velocities to the physical properties of sediments, fluids, and cement within the critical zone, and what factors most substantially influence the models’ accuracies? We answer these questions by testing and analyzing the accuracies of seven rock physics models (Hertz-Mindlin, Walton, Jenkins, Digby, stiff sand, soft sand, and contact [...]
The effects of 180 years of aging on the physical and seismic properties of partially saturated sands
Published: 2020-11-12
Subjects: Geophysics and Seismology, Physical Sciences and Mathematics, Sedimentology
Constraining how the physical properties and seismic responses of recently deposited sands change with time is important for understanding earthquake site response, subsurface fluid flow, and early stages lithification. Currently, however, there is no detailed (cm-scale) assessment of how sand physical properties and associated seismic velocities evolve over the first two centuries after [...]
Radiocarbon Protocols and First Intercomparison Results from the Chronos 14Carbon-Cycle Facility, University of New South Wales, Sydney, Australia
Published: 2020-11-12
Subjects: Physical Sciences and Mathematics
The Chronos 14Carbon-Cycle Facility is a new radiocarbon laboratory at the University of New South Wales, Australia. Built around an Ionplus 200 kV MIni-CArbon DAting System (MICADAS) Accelerator Mass Spectrometer (AMS) installed in October 2019, the facility was established to address major challenges in the Earth, Environmental and Archaeological sciences. Here we report an overview of the [...]
Evaluating the geochemistry and paired silicon and oxygen isotope record of quartz in siliceous rocks from the ~3 Ga Buhwa Greenstone Belt, Zimbabwe, a critical link to deciphering the Archean silica cycle
Published: 2020-11-09
Subjects: Physical Sciences and Mathematics
The balance of the Archean silica cycle links fundamentally to large scale processes that govern the composition of the ocean. Shifting contributions from continental or hydrothermal inputs of silica to the ocean is commonly recorded in silica-rich chemical precipitates. Such information is critical to interpreting primordial conditions in early life environments but reading the archive of [...]
Examining the impact of the Great Barrier Reef on tsunami propagation using numerical simulations
Published: 2020-11-09
Subjects: Other Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Coral reefs may provide a beneficial first line of defence against tsunami hazards, though this is currently debated. Using a fully nonlinear, Boussinesq propagation model, we examine the buffering capacity of the Great Barrier Reef against tsunamis triggered by several hypothetical sources: a series of far-field, Solomon Islands earthquake sources of various magnitudes (Mw 8.0, Mw 8.5, and Mw [...]
Fault inversion can accommodate ground deformation above inflating igneous sills
Published: 2020-11-09
Subjects: Physical Sciences and Mathematics
Magma emplacement is commonly accommodated by uplift of the overburden and free surface. By assuming this deformation is purely elastic, we can invert the shape and kinematics of ground deformation to model the geometry and dynamics of underlying intrusions. However, magma emplacement can be accommodated by viscoelastic and/or inelastic processes. We use 3D seismic reflection data to reconstruct [...]
Surface slip distributions and geometric complexity of intraplate reverse-faulting earthquakes
Published: 2020-11-09
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
Earthquake ground surface ruptures provide insights into faulting mechanics and inform seismic hazard analyses. Surface ruptures for eleven historical (1968 to 2018) moment magnitude (Mw) 4.7 to 6.6 reverse earthquakes in Australia are analyzed using statistical techniques and compared to magnetic, gravity, and stress trajectory datasets. Of the total combined (summative) length of all surface [...]
Thickness of the Saudi Arabian Crust
Published: 2020-11-05
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
We analyzed P-wave receiver functions from seismic stations covering most of Saudi Arabia to map the thickness of the crust across the Arabian plate. We present an update of crustal-thickness estimates and fill in data gaps for the western shield and the rifted margin at the Red Sea, as well as the eastern Arabian platform. Our application of a conventional H-k stacking algorithm included [...]
Preservation and re-exposure of late Palaeozoic glacial rock surfaces through cyclical burial and exhumation: apatite fission track evidence from the Fleurieu Peninsula, southeastern Australia
Published: 2020-11-05
Subjects: Earth Sciences, Physical Sciences and Mathematics
The antiquity of the Australian landscape has long been the subject of debate, with some studies inferring extraordinary longevity (>10^8 Myr) for some subaerial landforms dating back to the early Palaeozoic. A number of late Palaeozoic glacial erosion surfaces in the Fleurieu Peninsula, southeastern Australia, provide an opportunity to test the notion of long-term subaerial emergence, and thus [...]
The miscibility of Calcium Silicate Perovskite and Bridgmanite: A single phase perovskite in hot, iron-rich regions
Published: 2020-11-02
Subjects: Earth Sciences, Mineral Physics, Physical Sciences and Mathematics
Calcium silicate perovskite and bridgmanite are two phases believed to coexist throughout the lower mantle, which at some temperature, at least theoretically, dissolve into each other to form a single perovskite solid solution (CaxMg1-xSiO3). This may have large seismic and geochemical implications due to the changes in density, elasticity and element partition coefficients between single and [...]
An apparatus for measuring nonlinear viscoelasticity of minerals at high temperature
Published: 2020-10-30
Subjects: Physical Sciences and Mathematics
We describe a high-temperature, uniaxial creep apparatus designed to investigate nonlinear attenuation of materials over a wide range of temperatures (25–1300°C) using forced oscillations combined with a bias stress. This apparatus is primarily designed for investigation of minerals and rocks with high melting temperatures. An oscillatory compressional stress is used to determine attenuation and [...]
Morphodynamic modelling of beach cusp formation: the role of wave forcing and sediment composition
Published: 2020-10-29
Subjects: Physical Sciences and Mathematics
A field of beach cusps formed during a field experiment at Nha Trang Beach, Vietnam, under accretive conditions. The measured data was used to set-up morphodynamic simulations in XBeach, which was able to simulate cusp formation from an initially long-shore uniform beach profile. Several types of simulations were run in order to observe the resulting variation in mean cusp dimensions (length, [...]
Responses of tropical marine ecosystems to climate change impacts and their treatment in biogeochemical ecosystem models
Published: 2020-10-27
Subjects: Life Sciences, Physical Sciences and Mathematics
To predict the effects of climate change on marine ecosystems and the effectiveness of intervention and mitigation strategies, we need reliable marine ecosystem response models such as biogeochemical models that reproduce climate change effects. We reviewed marine ecosystem parameters and processes that are modified by climate change and examined their representations in biogeochemical ecosystem [...]